Figure 1.  Pathway of the thyroglossal duct. Drawing shows a lateral view of the embryologic thyroglossal duct from the foramen cecum through the developing hyoid bone to the pyramidal lobe of the thyroid. If the duct fails to involute completely, a thyroglossal duct cyst may result, with 80% of these lesions being at or below the level of the hyoid bone. (Reprinted, with permission, from reference 5.)